You can get fry-ed in Watery Ballroom of (fish) Romance 

Our Outdoors columnist Richard Collins on the latest Finnish research into a salmon's dangerous longing for love

A baby salmon first sees the light of day as a ‘fry’. It goes to sea when one to three years old. Returning as a young adult, it runs the gauntlet of weirs nets and fishermen’s hooks, swimming upstream to its childhood haunts on an empty stomach. Salmon don’t feed when they return to the river.

Scientists at the University of Helsinki took tissue samples from 5,000 salmon and genetically finger-printed them. Captives were tagged and returned to the wild, their ages known from the fish equivalent of tree-rings on their scales.